JP2005331281A - Vibration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration sensor having improved shock resistance so as not to lower sensitivity. <P>SOLUTION: This vibration sensor is equipped with a fixed electrode; and a diaphragm 3 whose surface facing to the fixed electrode functions as a vibration electrode, and whose surface on the opposite side to the vibration electrode has a deadweight 1. The sensor is used for outputting a vibration detection signal based on a capacitance change between the fixed electrode and the diaphragm 3. The diaphragm 3 is formed in the divided state by a plurality of slits 11 into a vibration part 33 positioned on the center part and equipped with the deadweight 1; a fixing part 31 positioned on a peripheral part, for fixing the diaphragm 3; and elastic support parts 32 having a narrow center part 32c and formed plurally at equal intervals in the circumferential direction, for connecting the vibration part 33 to the fixing part 31. The plurality of slits 11 are provided at equal intervals along the circumferential direction so that the end on the vibration part 33 side of each adjacent slit is overlapped in the radial direction with the end of the fixing part 31 side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a fixed electrode and a vibration plate having a surface facing the fixed electrode functioning as a vibration electrode and having a weight on a surface opposite to the vibration electrode, and the fixed electrode and the vibration plate The present invention relates to a vibration sensor that outputs a vibration detection signal based on a change in capacitance between the two.

  An electrostatic capacitance detection type, that is, an electret condenser microphone (hereinafter referred to as “ECM”) type vibration sensor is widely used in various applications including a microphone and a pedometer. Patent Document 1 discloses a technique of an ear microphone that detects bone conduction vibration. In this document, in order to satisfactorily detect a minute vibration called bone conduction vibration, a weight (weight) is attached to the movable electrode (corresponding to a diaphragm), and the mass of the movable electrode is substantially increased. A method for increasing the sensitivity by increasing the amplitude is shown. In addition, in order to improve the followability to high-frequency vibration, a method for improving the frequency characteristics by making the movable electrode into a piece with one end fixed or providing an annual ring-like slit is shown.

  Further, in Patent Document 2, in order to satisfactorily detect vibration in a low frequency (frequency) region such as when walking, a weight is applied to an impact applying means and a movable electrode that vibrates due to the impact applied by the impact applying means. The structure which provides is shown. That is, the vibration applying means transmits the vibration at a low frequency to the movable electrode, and the movable electrode is configured so as to have a higher natural vibration than the detected frequency, so that the vibration in the low frequency region such as when walking is satisfactorily performed. To be able to detect.

  Patent Document 3 discloses a technique related to a capacitive acceleration sensor that detects acceleration by converting a change in acceleration into a capacitance of a capacitor. According to this, in order to improve the sensitivity of detecting the capacitance between the movable electrode and the fixed electrode, the elastic body between the movable electrode and the outer peripheral portion for fixing the movable electrode is made into a plurality of beams. Thus, the displacement amount of the movable electrode is increased.

JP-A-59-79700 (FIGS. 2 to 3, FIG. 6, top of pages 1 and 2 and bottom left of page 3) Japanese Patent Laid-Open No. 10-9944 (FIG. 1, paragraphs 0006 to 0019) Japanese Patent Laid-Open No. 8-240609 (FIGS. 1, 6 and 2-3)

  By adopting the configuration as described above, it is possible to increase the inertial force and increase the sensitivity of the sensor. However, when the inertial force increases and the amplitude increases, the impact resistance during dropping is impaired. That is, there is a high possibility that the diaphragm is damaged or deformed by an impact. As a countermeasure, there is a method of providing a regulating member to regulate excessive displacement of the weight. In this case, unless the gap between the weight and the regulating member is narrowed, the regulating effect cannot be obtained sufficiently, and the diaphragm is allowed to be damaged or deformed. However, if the gap is made too narrow, the required amplitude is also restricted, so this gap needs to be provided with high accuracy. For this reason, accuracy is required for assembling. As a result, the assembling property is deteriorated, and there is a problem that the performance variation of the product becomes large due to an assembling error.

  In particular, in the case of the shape shown in FIG. 6 of Patent Document 3, the beam 8 has a very preferable beam for obtaining an elastic force, but the beam 8 is formed with the same width (hereinafter, in this paragraph). (The reference sign of reference 3). Therefore, when an excessive impact such as dropping is given, there is a high possibility that the joint between the movable electrode 1 and the fixed portion 11 and the beam 8 is damaged. Further, even when an impact is applied in the surface direction of the movable electrode 1, the movable electrode 1 is easily displaced, and the beam 8 is easily damaged or deformed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a vibration sensor with improved impact resistance while preventing the sensitivity of vibration detection from being lowered.

  The characteristic configuration of the vibration sensor according to the present invention for achieving the above object is that a fixed electrode and a surface facing the fixed electrode function as a vibration electrode, and a weight is provided on a surface opposite to the vibration electrode. A diaphragm, and outputs a vibration detection signal based on a change in capacitance between the fixed electrode and the diaphragm, and the diaphragm is positioned at a central portion by a plurality of slits. And a vibration part provided with the weight, a fixing part positioned at a peripheral part for fixing the diaphragm, a narrow central part, and a plurality of parts formed at equal intervals in the circumferential direction. And a plurality of slits in the circumferential direction so that the end portions on the vibrating portion side and the end portions on the fixed portion side of the adjacent slits overlap each other in the radial direction. Are provided at equal intervals along the line.

  According to this characteristic configuration, by forming the central portion of the elastic support portion to be thinner than both end portions, the elasticity can be improved, and sufficient sensitivity can be obtained by obtaining a sufficient amplitude. Even in the case of adding, both ends can be structured to be resistant to breakage and deformation.

  In the vibration sensor according to the present invention, the slit has an approximately S-shape that connects the outer track positioned on the fixed portion side, the inner track positioned on the vibrating portion side, and the outer track and the inner track. It is preferable to be composed of a connecting track.

  If a slit is comprised in this way, the said elastic support part can be formed in the part pinched | interposed into the said outer track | orbit and the inner track | truck which mutually overlap in radial direction. One end portion of the elastic support portion sandwiched between the end portion of the outer track and the inner track, and the other end portion of the elastic support portion sandwiched between the end portion of the inner track and the outer track. Is formed at a portion through which the substantially S-shaped connecting track passes. And the center part of the said elastic support part is comprised so that it may have a narrow width compared with the edge part of these elastic support parts. For this reason, sufficient amplitude can be obtained and sensitivity can be improved, and even when an impact is applied, a structure that is resistant to breakage and deformation can be obtained.

  In the vibration sensor according to the present invention, the slit may be formed by a spiral trajectory from the fixed part side toward the center of the vibration part.

  In the spiral track, the curvature of the track becomes larger (the radius of curvature is smaller) toward the center, and the curvature becomes smaller (the radius of curvature is larger) toward the periphery. That is, in the slit formed by the spiral track, the end portion on the vibrating portion side enters more into the center side, and the end portion on the fixed portion side extends to the peripheral portion. Therefore, the end on the vibration part side or the fixed part side of each slit is compared with the end on the vibration part side or the fixed part side of each elastic support part formed between adjacent slits. Thus, the central part of each elastic support part is formed to have a narrow width. Further, in this case, since the slit is formed by a series of curved orbits, the force resisting the impact in the surface direction of the diaphragm is increased. For this reason, sufficient amplitude can be obtained and sensitivity can be improved, and even when an impact is applied, a structure that is resistant to breakage and deformation can be obtained.

  Further, in the vibration sensor according to the present invention, the slit includes an outer track positioned on the fixed portion side, an inner track positioned on the vibrating portion side, and the outer track and the inner track in the radial direction. It can also be comprised from the connection track | orbit connected with a saddle type.

  According to this configuration, since the outer track and the inner track are connected in a saddle shape with a radial track, for example, the outer track and the inner track can be formed by arcs having different diameters. it can. The shape of the slit can be easily designed, and the elasticity and strength of the formed elastic support portion can be easily calculated.

  The said structure WHEREIN: It is preferable when the said diaphragm is comprised with either in stainless steel, tungsten, 42 alloy, Ti-Cu alloy, Be-Cu alloy, and SK material.

  When a material such as stainless steel, tungsten, or 42 alloy is used, the above-described diaphragm capable of obtaining good amplitude with good availability and workability can be configured. When Ti—Cu alloy, Be—Cu alloy, SK material or the like is used, the strength is further increased and the drop impact resistance is improved. As a result, a sufficient amplitude can be obtained to improve sensitivity, and a vibration sensor that is resistant to breakage and deformation can be obtained even when an impact is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a vibration sensor according to the present invention, and FIG. 2 is a cross-sectional view of the vibration sensor shown in FIG. As shown in FIGS. 1 and 2, the vibration sensor according to one embodiment of the present invention includes a fixed electrode 4 in which an electret layer 6 is formed on the inner surface of a housing 5, and a surface facing the fixed electrode 4 as a vibration electrode. And a vibration plate 3 having a weight 1 provided on the surface opposite to the vibration electrode. The weight 1 is displaced in a direction perpendicular to the surface of the vibration plate 3, and the fixed electrode 4 and the vibration plate 3 A vibration detection signal is output based on a change in electrostatic capacity between the two, and includes a regulating plate (regulating member) 2 that contacts the weight 1 and regulates the amount of displacement of the weight. .

  The fixed electrode 4 is provided at the bottom of a cylindrical housing 5 having an electret layer 6 formed on the inner surface and one end opened. A ring-shaped resin spacer 7 and the diaphragm 3 are attached to the bottom, and a predetermined interval of the capacitor portion for detecting a change in capacitance is provided by the thickness of the spacer 7. A weight 1 is attached to the diaphragm 3, a regulating ring 8 capable of regulating displacement of the weight 1 in the surface direction of the diaphragm 3 (hereinafter, “lateral direction”), and a direction orthogonal to the surface of the diaphragm 3 (hereinafter, The regulating plate 2 capable of regulating the displacement of the weight 1 in the “vertical direction”) and the gate ring 9 are sequentially stacked. Then, the structure is such that the vibration sensor is assembled by covering the substrate 10 on which the output circuit of the vibration detection signal is mounted and fastening it to the housing 5. In this structure, the diaphragm 3 is fixedly supported by being sandwiched between a spacer 7 and a regulating ring 8. Moreover, the housing 5, the regulation ring 8, and the gate ring 9 are made of metal. The regulating ring 8 also serves as a raising ring for forming an interval for obtaining a sufficient amplitude for the weight 1 that is displaced in a direction orthogonal to the surface of the diaphragm 3. Further, the restriction plate 2 has a hole 12 so that air existing between the restriction plate 2 and the weight 1 can be discharged well when the weight 1 is displaced in the vertical direction.

  FIG. 3 is a diagram showing an example of division formation of the diaphragm of the vibration sensor according to the present invention. As shown in FIG. 3, the diaphragm 3 includes a plurality of slits 11, a vibration part 33 that is located in the center and includes the weight 1, and a fixing part 31 that is located in the periphery and fixes the diaphragm 3. The elastic support portion 32 that connects the vibration portion 33 and the fixed portion 31 is divided. The elastic support portion 32 is located between one end portion 32 a that is a boundary portion with the fixed portion 31, the other end portion 32 b that is a boundary portion with the vibration portion 33, and both the end portions. It is formed in a beam-like body composed of a central portion 32c that is narrower than the portion. The elastic support portion 32 is continuously spaced along the circumferential direction so that the slits are continuous from the fixing portion 31 toward the vibrating portion 33 and the fixing portion side and the vibrating portion side of each adjacent slit overlap in the radial direction. By providing in, it forms in multiple numbers at equal intervals in the circumferential direction.

  When the elastic support portion 32 is formed in this manner, the vibration plate 3 can have a sufficient amplitude to improve sensitivity, and can have a structure that is resistant to breakage and deformation even when an impact is applied. The amplitude of the diaphragm 3, that is, the amplitude of the vibrating portion 33 is given by the elasticity of the central portion 32 c of the elastic support portion 32 of the beam-like body. Therefore, in order to obtain a large amount of this elastic effect, the elastic support portion is preferably formed to be elongated. However, since the end portions 32a and 32b of the elastic support portion 32, which is a boundary portion between the elastic support portion 32 and the fixed portion 31 or the vibration portion 33, serve as fulcrums of the elastic support portion 32 that is elastically moved, a certain degree of strength. It is preferable to be formed so as to be able to hold. This is to make it difficult to cause breakage such as cracks due to vibration and deformation due to torsion. Therefore, the center of the elastic support portion 32 is narrowed so that a large amount of deformation is applied to the central portion 32c of the elastic support portion 32. That is, the diaphragm 3 has a slit shape in which the central portion 32c of the elastic support portion 32 is formed narrower than both end portions 32a and 32b, so that the diaphragm 3 can obtain a lot of elastic effects and increase the strength. A good amplitude can be obtained over a long period of time.

  Further, in this example, even if the three elastic support portions 32 are provided in the circumferential direction and the vibration direction of the weight 1 is oblique to the direction perpendicular to the surface of the diaphragm 3, the vibration portion 33 is Excessive rocking is hardly caused with the diameter of the diaphragm 3 as an axis. For example, when the vibration sensor of this example falls and hits a side wall portion of the cylindrical housing 5 or a corner portion that is a joint portion between the housing 5 and the substrate 10 against the ground or the like, it is perpendicular to the surface of the diaphragm 3. It receives an impact in an oblique direction with respect to any direction. As a result, the weight 1 attached to the diaphragm 3 vibrates in an oblique direction with respect to a direction perpendicular to the surface of the diaphragm 3. If the arrangement of the elastic support portions 32 is axisymmetric with respect to the diameter of the diaphragm 3, the vibration portion 33 swings greatly about the diameter perpendicular to the direction of impact received by the vibration sensor.

  However, in this example, since three elastic support portions 32 are provided in the circumferential direction, the elastic support portions 32 are not line symmetric with respect to the diameter of the diaphragm 3. Accordingly, each elastic support portion 32 disposed asymmetrically with respect to the diameter of the diaphragm 3 acts to resist swinging about the diameter of the diaphragm 3. As a result, breakage and deformation of the diaphragm 3 can be satisfactorily prevented. That is, as shown in FIG. 3, when three or three or more odd numbers of slits 11 are provided, and three or three or more odd numbers of elastic support portions 32 are provided, the amplitude for improving the sensitivity of the vibration sensor is sufficient. The diaphragm 3 that is obtained and is strong against impact can be obtained.

  In FIG. 3, the slit 11 includes an outer track positioned on the fixed portion 31 side, an inner track positioned on the vibrating portion 33 side, and a substantially S-shaped connecting track connecting the outer track and the inner track. An example configured is shown. However, the shape of the slit 11 is not limited to this, and can also be formed by a spiral trajectory from the fixed portion 31 side to the center of the vibrating portion 33 as shown in FIG. In the spiral track, the curvature of the track becomes larger (the radius of curvature is smaller) toward the center, and the curvature becomes smaller (the radius of curvature is larger) toward the periphery. That is, in the slit 11 formed by the spiral track, the end portion on the vibration portion 33 side enters the center side more, and the end portion on the fixed portion 31 side spreads further to the peripheral portion. Therefore, the vibration part side end part 32b or the fixed part side end part of each elastic support part 32 formed between the slits on the vibration part side end part or the fixed part side end part thereof, respectively. Compared to 32a, the central portion 32c of each elastic support portion 32 is formed to have a narrow width. Further, in this case, since the slit 11 is formed by a series of curved orbits, the force that resists distortion against an impact in the surface direction of the diaphragm 3 is further increased. For this reason, sufficient amplitude can be obtained and sensitivity can be improved, and even when an impact is applied, a structure that is resistant to breakage and deformation can be obtained.

  Further, as shown in FIG. 5, the slit 11 is divided into an outer track positioned on the fixed portion 31 side, an inner track positioned on the vibrating portion 33 side, and the outer track and the inner track in a radial track. It can also be comprised from the connection track | orbit connected with a saddle type. If comprised in this way, since an outer track and an inner track are connected in a saddle shape with a track in the radial direction, for example, the outer track and the inner track can be formed by arcs having different diameters. The shape of the slit can be easily designed, and the elasticity and strength of the formed elastic support portion can be easily calculated.

  The diaphragm 3 may be made of stainless steel, tungsten, 42 alloy, Ti—Cu, Be—Cu, SK material, or the like. In particular, in the case where resistance to drop impact is not required, any metal material described above may be used as long as amplitude is obtained. Conversely, when resistance to drop impact is strongly required, a hard material such as Ti—Cu, Be—Cu, or SK material may be used. When such a material is used, the vibration in the surface direction of the diaphragm 3 is reduced, so that the regulation ring 8 that regulates this vibration is exclusively responsible for the function of the raising ring. As a result, the thickness of the regulating ring 8 in the radial direction can be reduced, and the cost can be reduced and the weight of the vibration sensor can be reduced.

  As shown in FIGS. 6 and 7, the weight 1 may have a hole 13 in the center and be formed in an annular shape. In this case, for example, the weight 1 can be widely attached in the radial direction of the diaphragm 3 with the same weight 1 as compared with the case where the weight 1 is formed in a columnar shape. As a result, when the weight 1 is displaced with excessive swing about the diameter of the diaphragm 3, the swinging angle of the diaphragm 3 is reduced because it contacts the restriction plate 2 outside the diameter. Can do. As a result, excessive displacement of the weight 1 can be suitably suppressed, and damage or deformation of the diaphragm 3 can be prevented.

  Thus, according to the present invention, it is possible to provide a vibration sensor with improved impact resistance so as not to lower the sensitivity.

The perspective view which shows an example of the vibration sensor which concerns on this invention Sectional drawing which shows an example of the vibration sensor which concerns on this invention The figure which shows the 1st example which divides and forms the diaphragm of the vibration sensor which concerns on this invention. The figure which shows the 2nd example which divides and forms the diaphragm of the vibration sensor which concerns on this invention. The figure which shows the 3rd example which divides and forms the diaphragm of the vibration sensor which concerns on this invention. The perspective view which shows the other example of the vibration sensor which concerns on this invention Sectional drawing which shows the other example of the vibration sensor which concerns on this invention

Explanation of symbols

1 Weight 3 Diaphragm (31: fixed part, 32: elastic support part (32c: center part), 33: vibrating part)
11 Slit

Claims (5)

A fixed electrode, and a surface facing the fixed electrode functions as a vibration electrode, and a vibration plate having a weight on a surface opposite to the vibration electrode,
A vibration sensor that outputs a vibration detection signal based on a change in capacitance between the fixed electrode and the diaphragm,
The diaphragm is formed by a plurality of slits.
A vibration portion provided at the center portion and provided with the weight;
A fixing part located at the periphery for fixing the diaphragm;
An elastic support part that has a narrow central part and is formed at equal intervals in the circumferential direction to connect the vibration part and the fixed part, and is formed separately.
The vibration sensor in which the plurality of slits are provided at equal intervals along the circumferential direction so that the end portion on the vibration portion side and the end portion on the fixed portion side of each adjacent slit overlap in the radial direction.   The slit is composed of an outer track positioned on the fixed portion side, an inner track positioned on the vibrating portion side, and a substantially S-shaped connecting track connecting the outer track and the inner track. The vibration sensor according to claim 1.   The vibration sensor according to claim 1, wherein the slit is formed by a spiral trajectory from the fixed part side toward the center of the vibration part.   The slit includes an outer track positioned on the fixed portion side, an inner track positioned on the vibrating portion side, and a connecting track that connects the outer track and the inner track in a saddle shape with a radial track. The vibration sensor according to claim 1 configured.   5. The vibration sensor according to claim 1, wherein the vibration plate is made of any one of stainless steel, tungsten, 42 alloy, Ti—Cu alloy, Be—Cu alloy, and SK material.

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